Surface thermodynamics and adsorption kinetics: surface tension and its associated properties

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Surface thermodynamics and adsorption kinetics of small molecules, surfactants, peptides, and polymers are of fundamental importance in various chemical and biomedical engineering systems. A central property in surface thermodynamics is surface tension. From the behavior of surface tension, one can infer changes in surface chemical composition as well as molecular adsorption. In the next five years, we will focus our studies on the surface tension and its associated properties of select chemical systems, with four specific objectives: 1. Surface tension of small, volatile, amphiphilic molecules in aqueous and non-aqueous solutions. We will generate both experimental data and theoretical understanding of the surface tension under various conditions. The outcome of this line of research will have significant impact on our understanding of surfaces and emerging nanotechnology advances. 2. Surface tension of water-gas mixtures under conditions relevant to extra-terrestrial environments. We propose to measure the surface tension of water surrounded with vaporous CO2 (the main component of the Martian atmosphere) at varied temperatures and pressures. We will correlate the vapor pressure of CO2 with the water surface tension, providing data to predications of water content in the mesoporous soils of Mars. 3. Surface tension and associated properties of self/co-assembling peptides in aqueous solution. We will exploit our expertise in surface tension and extract important information about experimental conditions under which the newly designed amino acid pairing peptides assemble. The outcome will provide means to control peptide nanostructures for nano-biotechnology applications, especially for drug and gene delivery. 4. Surface tension of polymer melts in supercritical fluids under polymer processing conditions. We will measure the surface tension of polymer melts under high pressure and temperature, with/without mesoporous particles. The results will be explained by theoretical modeling based on self-consistent field theory. The outcome will have direct application to micro/nanocellular foaming of plastics.